Two fair dice are rolled together 288 times, and each time it is noted whether the two dice show the same number. Using the probability of that event, in about how many of the 288 rolls would you expect the two dice to match?

The two dice match on 6 of the 36 equally likely throws — (1,1), (2,2), (3,3), (4,4), (5,5) and (6,6) — so a match has probability 6/36 = 1/6. Over 288 rolls the expected number of matches is $288\times 1/6=48$. Trap 8 = 288/36 uses 1/36, which is the chance of one PARTICULAR matching throw such as (4,4), and forgets that there are six such throws. Trap $72=288\times 1/4$ and trap $24=288\times 1/12$ come from mis-sized probabilities; the quick sanity check is that a 1-in-6 event should turn up in roughly a sixth of the trials.